So on FC26 (beta) as well. Same problem. The question how do you force the OpenSSL libraries to downgrade when they are at the lowest level. You have to force FC25 vesion but you get a conflict install since removing openssl also removes DNF which is protected and not authorized to be removed?

No need to replace OpenSSL. Keep the F26 version. Only need to replace the F26 version of MakeMKV (and mmdtsdec..) with the F25 version. Simplest to just d/l the RPMs from the F25 repository, and then use # rpm -Uvh <rpmname> --force --nodeps